1. Field of the Invention
The present invention relates to a four-way change-over valve for an air conditioner used to switch cooling and heating operations in the air conditioner utilizing a refrigerating cycle of a heat pump type. The present invention also relates to a service valve with a four-way change-over valve for an air conditioner. The present invention further relates to a valve attached to an outdoor unit of an air conditioner of a separating type in which the same piping function is fulfilled by using one compact valve instead of two general valves.
2. Description of the Related Art
In the general structure of a four-way change-over valve utilizing a refrigerant pressure, a valve sheet having a U-shape in cross section and the same curved surface as a cylinder must be accurately soldered to a central lower portion of a cylinder. Further, this structure has a connecting means for connecting a valve slide arranged on an upper face of the valve sheet to a piston rod or a bracket such that the valve slide is set in a press contact state at any time and can be smoothly slid. This structure also has a fixing means for fixing piston rings to both ends of the piston rod. However, operability of each of the connecting and fixing means is greatly reduced since the valve slide is located in a central portion of the cylinder.
In this structure, differences in pressure between chambers of the cylinder are caused by using magnetomotive force as attractive force and resilient force of a spring as repulsive force in a switching operation of the change-over valve and one generation of the magnetomotive force and demagnetization. Thus, the valve slide is slid at all strokes. Accordingly, in a heating state of an air conditioner, no pressure differences between the chambers for making a heating circuit can be held unless an electric current continuously flows through a solenoid. Therefore, no valve slide can be held in the heating state.
In a change-over valve using a wax type thermoelement, pressures with the chambers are increased by heating the thermoelement in a driving source. Accordingly, an error in operation of the change-over valve tends to be caused, or a switching operation of the change-over valve tends to be unstable by the influence of an outside air temperature. Further, performance of the change-over valve is greatly influenced by a seal state between a shaft in a shaft core portion and the wax type thermoelement. However, it is very difficult to reliably seal the shaft and the wax type thermoelement when the change-over valve is manufactured. As a result, cost of the change-over valve is increased.
In a change-over valve using a stepping motor, etc., the stepping motor is very expensive so that cost of the four-way change-over valve is increased.
In each of change-over valves shown in Japanese Utility Model Application Laying Open (KOKAI) No. 58-127276 and Japanese Patent Application Laying Open (KOKAI) No. 59-155669, an electromagnetic coil is arranged outside a device body through a pipe-shaped guide. A plunger is inserted into this guide and a valve body within the device body is swung through an operating plate. Therefore, the device body is made compact, but the electromagnetic coil is large-sized so that the electromagnetic coil projects toward the exterior of the device body. Accordingly, the device body and the electromagnetic coil are unbalanced. Further, it is very troublesome to airtightly connect the device body to the electromagnetic coil through the guide. Accordingly, such a structure is not practically used.
In another general valve structure, two valves are attached onto the side of an outdoor unit of a general air conditioner of a separating type. The two valves are composed of a 3/8" valve connected to a four-way change-over valve and a 1/4" valve connected to a capillary tube. Piping of these valves is performed between the outdoor unit and an indoor unit when the air conditioner is arranged.
For example, Japanese Utility Model Application Laying Open (KOKAI) Nos. 61-54563 and 61-54564 show a proposed valve structure for integrating two valves as one valve unit.
In the general valve structure using two valves, the two valves are independently manufactured so that cost of the valve structure is increased and a wide space for attaching the valves is required, Further, a valve having a shaft shape is used within the valve structure so that the valve structure is increased in height. Further, there are no opening and closing displays with respect to the valves so that no operator can accurately attach the valves to the air conditioner unless the operator is a technical expert for attachment.
In the valve shown in each of Japanese Utility Model Application Laying Open (KOKAI) Nos. 61-54563 and 61-54564, one valve device body is formed in a cylindrical shape. However, a valve within this valve device body is constructed by a valve having a shaft shape. In Japanese Utility Model Application Laying Open (KOKAI) No. 61-54563, a main valve rod has a second valve rod therein and is mounted to the valve device body such that the main valve rod functions as two valves. In contrast to this, in Japanese Utility Model Application Laying Open (KOKAI) No. 61-54564, a ring-shaped valve body is formed such that an elongated central valve rod is inserted into a central portion of the ring-shaped valve body. This ring-shaped valve body is mounted to the valve device body. Connection holes formed in a central portion and a lower end portion of the valve device body are opened and closed by each of the valve rods. However, each of the valve structures in these two applications is complicated so that it takes much time and labor to process each of the valve structures.
Further, in each of these valve structures, the shaft-shaped valve is arranged as a double structure within the valve device body so that each of the valve structures is increased in height. Accordingly, piping connection holes connected to an indoor unit are directed outward so that no pipes are preferably arranged in appearance.